Reproducibility of different arrangement of resin copings by dental microstereolithography: Evaluating the marginal discrepancy of resin copings

Statement of problem: Microstereolithography (μ-SLA), a form of additive manufacturing, can produce one or more platforms of resin copings. However, no evaluation has been made of the variation in marginal discrepancy using this method, even though this is an important factor for a successful restoration. Purpose: The purpose of this in vitro study was to evaluate the reproducibility and marginal discrepancy of resin copings fabricated using dental μ-SLA. Material and methods: A master die of a mandibular right first molar tooth was made from Type IV stone and scanned to produce a stereolithography file. Resin copings were then fabricated using μ-SLA additive manufacturing by repeating 1, 3, or 6 arrays to give a total number of 18. The marginal discrepancies of these resin copings were measured using digital microscopy (at ×160 magnification), and the data obtained were analyzed using a nonparametric Kruskal-Wallis H test, post hoc Mann-Whitney . U-test, and Bonferroni correction. Results: The mean ±SD total marginal discrepancies of 1, 3, and 6 arrays were found to be 72.2 ±39.1 μm, 61.2 ±37.3 μm, and 92.5 ±54.1 μm. Statistically significant differences were found among the compared groups (P<.05). Conclusions: Based on the marginal discrepancy, μ-SLA of additive manufacturing is more precise when 3 arrays are used than when 1 or 6 arrays are used on a single build platform. Because the fit is affected by the number of copings fabricated, further research of multiple resin copings is required.